Comparative Study on Different National Standards for Local Post Weld Heat Treatment of Pressure Vessels

Abstract In order to eliminate these welding residual stress which produced in the process of pressure vessel manufacturing and assembling, post-weld heat treatment is required for the weld structure. The Large size and complex structure pressure vessel which cannot integral post-welding heat treatment always implement local post-welding heat treatment. The reasonable heated band and insulated band are particularly important in the procedures of local post-welding heat treatment to meet the requirements of pressure vessel heat treatment. The recommended heated band and insulated band are given in different national standards. But the recommended width of heated band and insulated band are different in different national standards. In the paper, numerical simulation was carried out to compare and study the difference of temperature distribution in the holding temperature period when post-welding heat treatment of pressure vessel barrel butt weld. The result show that the temperature distribution on sock band is very closed when the barrel butt weld implements post weld heat treatment with the heated and insulated band recommended in ASME BPVC-VIII-2017 and EN 13445-4:2014. The axial temperature gradient on sock band is very small and the temperature difference almost comes from the temperature difference through the thickness. Compared with this, the axial temperature gradient is larger and the temperature difference through thickness is smaller when post weld heat treatment with the max recommended heated and insulated band given in GB/T 30583-2014.